1. Field of the Invention
The present invention relates to a heat exchanger and, more particularly, to a heat exchanger which is effective when applied to a radiator of large construction vehicles such as bulldozers and shovel loaders and agricultural vehicles such as farm tractors.
2. Description of the Related Art
Radiators for special-purpose vehicles such as large construction and agricultural vehicles are made up of a plurality of small radiators or a plurality of heat exchanging units which are arranged in parallel with the flow of cooling air, and each heat exchanging unit has the same construction as a normal radiator which is made up of a plurality of tubes through which coolant is caused to flow (for example, see Japanese Unexamined Patent Publication No. 5-215475).
Incidentally, as the dimension of a location of the heat exchanging unit which extends in parallel with the longitudinal direction of the tubes, that is, the height of the single heat exchanging unit, is larger than the width of the single heat exchanging unit, that is, the dimension of a location of the heat exchanging unit which extends to intersect with the longitudinal direction of the tubes at right angles, the single heat exchanging unit forms a long elongated pillar-like shape.
In addition, as each heat exchanging unit is assembled to the special-purpose vehicle such as the construction vehicle via header tanks which communicate with each heat exchanging unit, the long elongated pillar-shaped heat exchanging unit is constructed to be supported at longitudinal ends thereof. Due to this, the heat exchanging unit is easily caused to resonate at a primary frequency of a large amplitude having nodes at the longitudinal ends thereof.
To cope with this, while there are countermeasures in which an angle member is provided at a substantially longitudinal center of the plurality of tubes which constitute the heat exchanging unit for connecting together the respective tubes thereat, and a connecting bar to which the angle member fixed to each heat exchanging unit is connected, is fixed to the vehicle, these countermeasures have the following problems.
Namely, in the aforesaid countermeasures, as the angle member is directly fixed to the tubes, an impact force applied to the angle member is transmitted directly the tubes, and this increases a probability that damage such as cracking is generated in the tubes.
In addition, in a case where a corrugated fin is joined to the external surface of the tube, the respective tubes cannot be connected to the angle member using a means for making insertion holes in the angle member so that the tubes are passed through the insertion holes so made.
Furthermore, as it is difficult for cooling air to flow into the heat exchanging unit (a core portion) at a location of the heat exchanging unit where the angle member is provided due to the angle member constituting an obstacle, the radiator cannot sufficiently exhibit its heat radiating capacity.